1. Field of the Invention
The present invention relates to a main device redundancy configuration for allowing another main device to act as a substitute master main device if a plurality of main devices are arranged and one main device acting as a master malfunctions, and a main device replacing method.
2. Description of the Related Art
There is conventionally known a technique for connecting main devices to one another by a network and for allowing each of the main devices to use functions of the other main devices. The “main device” means herein a device that includes an interface for accommodating a terminal (e.g., a button telephone), an interface connecting the main device to a public line, and an interface connecting the main device to an IP network.
However, to enable the main devices to mutually use functions of the others via the network, it is necessary to alternate their functions, respectively. The non-alternated functions are not compliant with the network, so that the other main devices are incapable of using all functions of a certain main device via the network.
Namely, with the conventional technique, in the architecture of networking connection among the main devices, CPUs of the main devices manage resources, respectively and manage states of terminals, lines and the like separately. Due to this, to enable each of the main devices to actuate the functions of the other main devices via the network is not so simple as actuating its own functions but it is disadvantageously necessary to alter the functions so as to be compliant with the network.
Furthermore, in case of conventional networking systems, the systems manage slots for packages that are resources of each main device separately. Due to this, each system is unable to know information, states, and the like of resources of the other systems. As a result, restrictions are imposed on use of functions of the other main devices on the network.
An object of a reference embodiment to be described below is to construct a networking system architecture that can facilitate managing information and that is free from restrictions to functions by allowing one main device to integrally manage information such as resources of hardware of all main devices connected to one another by a network.
The gist of the reference embodiment lies in a technique for allowing each main device to handle resources on the network as if they are its own resources.
In the main device operating under program control, hardware resource management, that is, management of terminals, lines and the like is made in the form of package management.
Therefore, to allow each main device to handle resources on the network as if they are its own resources, it suffices that the main device handles packages on the network as if they are its own packages.
FIG. 1 is a conceptual diagram of package management on the network.
If a package is installed into a main device 2, information on the package and information on a terminal, a line and the like connected to the package are transmitted to a main device 1 via the Ethernet (registered trademark).
On the main device 2 side, since these pieces of information are not transmitted to a package control unit or a call control unit of the main device 2, it does not appear to the main device 2 that a situation changes.
On the main device 1 side, since a lower layer processes data transmitted from the main device 2 and it appears as if the information arrives from a slot of the main device 1, it appears to the main device 1 that the package is input to the slot of the main device 1.
Furthermore, as for a command to the package (downstream data), a lower layer of the main device 1 processes the downstream data and transmits a command to a virtual package to a real package on the network.
By introducing this mechanism, it is possible for each main device to handle resources on the network as if they are its own resources.
Therefore, a higher layer of each main device such as the call control unit can freely use resources without knowledge that the resources are present on the network.
FIG. 2 is a configuration diagram of the networking system architecture according to the reference embodiment.
A main device managing all the resources on the network and exerting all call controls is referred to as “master”.
A main device connected to the master, providing package information to the master, and obeying commands from the master is referred to as “slave”.
To establish the networking system architecture according to the reference embodiment, it is necessary that one of a plurality of main devices constituting the network acts as a master. All slaves are connected to the master, obey commands from the master, and do not perform any processings such as call control. Namely, even if a slave includes a functional unit performing call control or the like, the unit is in a dormant state.
The master can control a plurality of slaves and can handle resources of the main devices connected to the master as slaves as if they are all its own resources.
The networking system architecture constituted by the master and the slaves can thereby act as if it is one system.
It is necessary to set, in advance, information as to which main device acts as a master or a slave and information as to by which IP address each of the main devices is connected to the master.
The main device set as the master awaits connection from the slaves and each of the slaves establishes connection to a preset IP address of the mater.
In this way, after the connection between the master and the slaves is established, transmission of package information and the like are performed and the networking system architecture operates as one system.
If the master goes down, all the main devices connected to the master become unavailable. To prevent this problem, if the master goes down, one of a plurality of slaves acts as a master to execute roles of the master for the original master (Redundancy Function).
It is necessary to set, in advance, information as to which slave substitutes for the master if the master goes down.
A specific method for central control over resources on the network will next be described.
FIG. 3 shows a system configuration on the networking system architecture.
Only one master is present on the network and controls all slaves.
To identify each system on the network, the systems are given unique system IDs, respectively.
FIG. 4 is a conceptual diagram of slot management according to the reference embodiment.
Packages are physically installed into slots of each of the systems connected to the network and having the system ID. Information on the packages is unitarily integrated into a virtual slot database and the master system manages the virtual slot database.
The master controls slots while referring to this virtual slot database.
If slots belong to the system other than the master, the slots are present physically at a remote location connected to the master by an IP network. However, the master can handle the slots as if they are its own slots without knowledge that the physical slots are at remote locations.
Therefore, the master can handle terminals and lines connected to the packages installed into the slots as if they are terminals and lines connected to the master.
FIG. 5 shows the systems representing the above-stated manners.
Packages connecting terminals, packages accommodating therein lines connected to a public line, and packages accommodating therein IP lines connected to the IP network are installed into a system having system ID: 1, a system having system ID: 2, and a system having system ID: 3, respectively.
Since physical slots of these systems are managed as virtual slots in the virtual slot database, each of the systems can freely control the terminals, lines and the like accommodated in the packages connected to the slots as if they are its own terminals, lines and the like.
By adopting the resource management method, even the systems distributed on the network can use functions of the other systems without restrictions.
As shown in FIG. 3, the systems shown in FIG. 5 are built on a client-server architecture in which one master controls slaves. The master performs call processings on all the main devices including the master and manages a database. The master also manages virtual slots.
The systems are connected to one another according to an internet protocol (IP) and given system IDs unique to the systems, respectively.
The systems 1, 2, and 3 include packages accommodating therein terminals, packages accommodating therein ordinary lines, and packages accommodating therein IP lines, respectively.
The virtual slot database manages information on these packages. While the master basically manages the data, each of the slaves holds the same data in case of replacement of the master.
The example shown in FIG. 5 will be additionally described from viewpoints of data flow.
FIG. 6 shows data flow for conventional package control.
As shown in FIG. 6, upstream data from a package is transmitted from a slot I/F module 101 to a CAPS (call control module)/OPMS (package and terminal management module) 105 via an IOCS (input/output control module) 103.
The CAPS/OPMS 105 processes the upstream data and transmits a downstream command to the slot I/F module 101 via the IOCS 103. For example, if a package is installed into a slot, then data is transmitted to the CAPS/OMPS 105 as upstream data, and the CAPS/OMPS 105 recognizes package installation and exercises a starting control over the package, i.e., permits the package to be active. If a terminal connected to the package installed into the slot is off the hook, the slot I/F module 101 transmits data indicating that the terminal is off the hook to the CAPS/OPMS 105 as upstream data. In response to the upstream data, the CAPS/OPMS 105 transmits a command to produce a dial tone from the terminal to the slot I/F 101 via the IOCS 103 as downstream data.
In FIG. 6, the data from the slot I/F 101 is directly transmitted to the higher module as input data, so that the system concerned can naturally control only the slot connected to the system.
FIG. 7 shows data flow according to the reference embodiment.
As shown in FIG. 7, in the reference embodiment, slot management by networking is realized by additionally providing slot control modules 107 each controlling slot input/output and a slot management module 109 managing slot information.
Upstream data from one slot is subjected to a temporary spooling by one of the slot control modules 107 corresponding to a system including the slot and then transmitted to the slot management module 109 of the master controlling the system. If the system is the master, the upstream data is transmitted to its own slot management module 109. The management module 109 exercises such a control that it appears to the IOCS 103 that is a higher module that the data transmitted to the slot management module 109 is transmitted from a certain slot.
Operation performed by the slot management module 109 will be described in more detail with reference to a table of FIG. 8.
If the slot management module 109 receives data from a specific slot of a certain system and the specific slot is a slot of the system that has not been recognized so far, the slot management module 109 newly assigns a virtual slot number to the slot and subsequently regards the slot of the system as the slot to which the virtual slot number is assigned.
For example, if upstream data is transmitted from a slot 1 of a system 1 and the slot 1 is the slot that has not been recognized so far, a virtual slot number 1 is assigned to the slot 1.
In this manner, if virtual slot numbers are newly assigned to slots so as to act as virtual slots, respectively, a physical slot/virtual slot contrast table 111 as shown in FIG. 8 is created.
Thereafter, the higher module such as the IOCS 103 or the CAPS/OPMS 105 regards the data transmitted from the slot 1 of the system 1 as data from its own slot 1 even without knowledge of the network.
If downstream data is to be actually transmitted to a slot to issue a command to hardware, the command is issued to a slot of an appropriate system while referring to the physical slot/virtual slot contrast table 111.
The command is transmitted to the slot control modules 107 of the systems and commands are transmitted to actual packages of the systems, respectively.
In this manner, by introducing the modules 107 and 109 controlling or managing slots on the network, there is no need to have knowledge of the network during most parts of the processings performed by the main devices, and it is possible to control hardware as if the module controls the system corresponding to the module.
Differently from hardware limitation on the number of physical slots, no limitation is set to the number of virtual slots but an unlimited number of virtual slots can be assigned as long as a memory of each system can afford.
Generally, in each of the systems, processings are performed using virtual slot numbers. However, in parts visible to a user, such as setting of system data, it is often desired to perform a processing while identifying by which slot in which system the processing is performed.
In that case, settings and the like can be made using physical slots while referring to the physical slot/virtual slot contrast table 111.
The reference embodiment solves many of the conventional problems by attaining the central control networking system architecture so as to avoid problems with a distributed networking system architecture.
At the same time, however, the reference embodiment disadvantageously bears system vulnerability. Namely, according to the reference embodiment, from the nature of the reference embodiment, one main device acting as the master (hereinafter, “master main device”) exercises central control over all the resources on the network and manages all the main devices acting as slaves (hereinafter, “slave main devices”). Due to this, if the master main device malfunctions due to some failure, all the slave main devices connected to the master main device malfunction accordingly, with the result that the entire network malfunctions.